There is a receiving apparatus which receives an optical signal transmitted from a light emitting element by use of a light receiving element. Such receiving apparatus converts a current signal obtained by receiving an optical signal into a voltage signal and compares the voltage signal with a predetermined threshold voltage to thereby generate and output a digital signal.
However, in the receiving apparatus, when the signal level of voltage signal is large and saturation occurs (ie., the dynamic range is exceeded), there may be a case where the digital signal cannot be properly generated. In order to prevent this phenomenon, there has been proposed that, in the receiving apparatus, the signal level of voltage signal is adjusted so that a threshold voltage is positioned substantially near the center of the amplitude range of the voltage signal and then comparison with the threshold voltage is performed to conduct binarization. The names of documents on the receiving apparatus which receives an optical signal are described below. Japanese Patent Laid-Open No. 2004-179982 (FIG. 1) Japanese Utility Model Publication No. 8-4755 (FIG. 1)